The present invention relates to a nutrient medium carrier system consisting of a nutrient medium carrier, a covering, and a sealing foil.
Nutrient medium carriers filled with a nutrient medium serve the purpose of culturing microorganisms and of determining microorganisms, i.e. ascertaining their presence and quantity.
For inoculation with microorganisms, so called Petri dishes have been used until now. The bottoms of these are covered with a layer of a nutrient medium, and they may be either round or rectangular. The bottoms may be plain or partitioned. These dishes are closed with a cover that can be put on top of them (cf. Greiner, Labortechnik fur Medizin und Forschung, 1976: 35-36).
Surface contact cultures or so-called dip slides serve for the identification of localized microorganisms. Until now contact dishes were used for surface contact cultures. These are shaped like Petri dishes, buty they have a lower edge, above which the nutrient medium projects.
The so-called dip slides are strips coated with a nutrient medium, which are selaed up in a little tube with a stopper or similar seal that cannot be penetrated by microorganisms, and which can be used for determining microorganisms in liquid media.
A device for testing the air for its microorganism content is known, moreover, from German Pat. No. 2,301,385, and in this device a carrier foil that is coated with a nutrient medium is used, which corresponds in length to the width of the device, and which is divided up into cups to receive the nutrient medium.
Both Petri dishes and contact dishes and dip slides are relatively expensive, and at the same time, both types of dishes, moreover, involve a high risk of contamination, especially during shipping, too, since they can not be tightly sealed before use.
Beyond this, each of the three types of container requires separate handling, separate instruments, etc., and the user who is concerned with all three types of determining microorganisms needs to keep a separate inventory of each of these containers.
Petri dishes have been used essentially unchanged, for microbiological tests, practically since the time of Robert Koch, that is, for about 100 years. The only change is that plastic is used today as the material for the dishes, as well as the glass that was originally used. The Petri dish system could be looked upon as somewhat satisfactory and useful as long as it was mainly applied for the needs of a small group of users and the tests were carried out on a small scale.
With increasing technology and rationalizing, the need arose for a system that is easier and more economical with regard to manufacturing, provides standardized quality, and is protected from secondary contamination.
The foil described in German Pat. No. 2,301,385, to be sure, also has sterile packaging, but after the sealing foil has been removed, and after use for testing the air for its microorganism content, the nutrient medium carrier can no longer be automatically affixed to the covering. The system can only be sealed with the aid of an adhesive strip, or a slide, or similar measures. Besides, the foil is fashioned in such a way that it can be specially used only in the device intended for it.
It was the objective of the present invention, therefore, to manufacture a hermetically sealed, multi-purpose container that could not be penetrated by microorganisms, which ought not only to replace the Petri dish, but can also be used for surface contact cultures and determining microorganisms in fluids, which can be made economically in a rational manner, the seal of which can not be penetrated by microorganisms even during shipment, and which can be adequately sealed again after inoculation until incubation.